From sunset to sunrise and during other times of reduced visibility, boaters are required to display navigation lights pursuant to U.S. Coast Guard regulations so that the operators of other marine craft can easily determine the position and direction of movement of such craft. In addition to requiring a red port side bow light and a green starboard side bow light, marine craft operators are required to display a white light either at the stern of the marine craft or at another position aft of the bow lights and at a certain elevation. The white light should project an uninterrupted beam of light in all directions in a horizontal plane, i.e. project light radially in all directions substantially perpendicular from a vertical axis to provide a continuous pattern of light which is visible to other boaters in the vicinity regardless of their position relative to the light. Hence, such lights are commonly referred to as "all-round lights" or "360 degree lights."
Although all-round lights, used in combination with the red and green bow lights, have increased boating safety by alerting operators of marine craft of the relative position and movement of other craft after sunset and during other times of reduced visibility, there have been many reported incidents of conventional all-round lights causing glare which can interfere with the ability of a boat operator to see clearly at night. Additionally, there have also been some reported incidents of accidents occurring because of a boat operator experiencing temporary night blindness after looking directly in the direction of the all-round light. Such problems have occurred with conventional all-round lights because the light has not been effectively focused or directionally limited to project light only outwardly in a relatively narrowly defined horizontal direction. To the contrary, conventional all-round lights generally have a relatively large cylindrical or drum-shaped lens which is designed to emit light in substantially all directions, except possibly in a straight upward and/or straight downward direction. Because of the relatively wide band of light emitted from conventional all-round lights, there is a significant possibility that a marine craft operator who glances rearwardly for only a moment can experience temporary night blindness on account of light from the all-round light shining directly into the operator's eyes. Further, glare from conventional all-round lights which emit a relatively wide band of light create relatively large brightly lighted areas on the water near the boat adjacent to areas which are in shadows cast by portions of the boat interposed between the water and the light. Such contrasting light and dark areas can make it difficult to see objects which are in the shadows, especially any such objects which are in the shadows near the brightly lighted areas. Accordingly, there is a perceived need for an all-round light which performs equivalently to conventional all-round lights with respect to adequately warning other boaters of the position and direction of movement of a marine craft to which it is appropriately mounted, while reducing or eliminating problems associated with glare and temporary night blindness. Further, it is desirable to fulfil the forgoing perceived needs with an all-round light which has a relatively traditional appearance which will be accepted by those who build and sell, as well as those who own and operate, marine craft. More specifically, it is desirable to provide an all-round light having a relatively large lens, but which emits light in a directed or limited pattern that reduces or eliminates problems associated with glare, while also providing a continuous pattern of light which is adequately visible to other boaters in the vicinity regardless of their position relative to the light.
Another disadvantage with conventional all-round lights, which generally comprise a lighting fixture connected to one end of a pole, is that they are designed to be properly mounted to a marine craft in only a single orientation, usually with the longitudinal axis of the pole being arranged vertically or at a slight angle with respect to a vertical line. More specifically, conventional all-round lights generally cannot be mounted to a variety of different surfaces which are sloped at an angle which is significantly different from that which the light is designed to be mounted (e.g. horizontal or at least substantially horizontal) while providing a continuous, uniform pattern of light which is equally visible to other boaters irrespective of their position relative to the light. For example, an all-round light having a base with a lower end connected to a pole and an upper end connected to a cylindrical or drum-shaped lens having a top or cap and a cylinder axis which is aligned with the length of the pole, must be mounted to the marine craft so that the pole is in an approximately vertical orientation, as any major deviations from the vertical orientation will cause the base and the top or cap of the light to block light emitted from the lens, creating a pattern of light on the horizon which is not uniform. As a specific example, if a typical all-round light is mounted to a surface which slopes downwardly and rearwardly at a 45 degree angle, then the cylindrical lens will also slope rearward at a 45 degree angle such that visibility of the light will be adequate for other boaters situated on the starboard or port side of the boat on which the all-round light is mounted, but visibility of the light will be relatively poor for any boaters situated on the fore and aft ends of the boat on which the all-round light is mounted, thus reducing safety. A possible solution to this problem is to manufacture a variety of different all-round lens which are adapted to be mounted to surfaces which are sloped at different angles. However, this is not an economically practical solution, as it would significantly increase manufacturing, packaging and inventory costs. Accordingly, there is a need for an all-round light which can be mounted to a variety of differently sloped surfaces, as well as horizontal surfaces, and which is adjustable to project a narrow band of light in all directions along only the horizon to alert other boaters in the vicinity of the position and heading of the boat to which the light is attached without shining light directly into the operators eyes or creating other problems with glare.